Method for producing grooves in formed thermoplastic insulation boards

ABSTRACT

Smooth-walled grooves are formed in thermoplastic insulation boards without bothersome generation of &#39;&#39;&#39;&#39;dust&#39;&#39;&#39;&#39; by first forming a pair of continuous slits in the board and thereafter removing the material from the area defined by the slits with a heated, knife-edged tool configured to direct the material outwardly of the board, to produce a smooth bottom wall and to separate the material in the form of a continuous strip.

0 United States Patent 1191 [111 3,

DerMarderosian et a1. Dec. 9, 1975 [54] METHOD FOR PRODUCING GROOVES IN2,867,222 1/1959 Otto B12 a1 132/39 FORMED THERMOPLASTIC INSULATION2,896,059 7/1959 219/21 BOARDS 2,991,214 7/1974 Burkholder 154/1183,062,698 11/1962 Aykanlan 156/306 [75] Inventors: DikrunDerMarderosian, Sudbury; 3,180,778 4/1965 Rinderspacher et a1... 156/311Paul Albe t Tremblay, Billerica, 3,301,935 l/1967 Stackhert 264/321 b hf Mass 3,330,174 7/1967 Hazen et a1...

3,338,122 8/1967 [73] Assignee: W. R. Grace & Co., Cambridge, 3,491,651l/ 1970 Mass. 3,555,137 l/l97l 3,610,078 10/1971 Fllfidl June 24, 77 77/ 97 3,693,253 9/1972 [21] Appl. No.. 482,143 3,709,094 H1973 RelatedU.S. Application Data 3,736,820 6/1973 [62] Division of S61. N0.314,685, Dec. 13, 1972, 33501222 11/1974 abandoned- FOREIGN PATENTS ORAPPLICATIONS 994,393 6/1965 United Kingdom U.S. G y [51] Int. Cl. B26D3/06 Fleld of Search 7, 9, 16, Examiner Frank Yost 219/221 Attorney,Agent, or FirmC. E. Parker; William L. Baker [56] References CitedUNITED STATES PATENTS 57 ABSTRACT 362,179 5/1887 Remus 83/5 s n grOOveSare formed in thermoplastic g h insulation boards without bothersomegeneration of n ersonw dust by first forming a pair of continuous slitsin the 1,751,549 3/1930 Hope et al.. 83/5 1,940,106 12/1933 Synder .183/5 board and thereafter f' f the matenal f the 1,955,395 4/1934Tlletll 83/171 x area defined by the 511$ a heated, knlfe-edged 1,9 7,22 1 1934 Robinson et 1 33 5 tool configured to direct the materialoutwardly of the 2,157,151 5/1939 Stackhouse 83/171 X board, to producea smooth bottom wall and to sepa- 7 1 1943 nports 83/5 rate the materialin the form of a continuous strip. 2,655,190 10/1953 Mason et a1....83/5 2,692,328 10/1954 Jaye 132/39 3 Clams 4 Dmwmg Figures US. PatentDec. 9 1975 Sheet 2 of2 3,924,496

METHOD FOR PRODUCING GROOVES IN FORMED THERMOPLASTIC INSULATION BOARDSThis is a division, of application Ser. No. 314,685, filed Dec. 13,1972, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to the manufacture ofinsulating boards, especially insulating boards made from cellularthermoplastic materials such as foamed polystyrene.

Insulation boards of cellular plastic material such as cellularpolystyrene, polyurethane, etc., have been widely employed as theinsulation medium in building and other constructions. Foamed boardsprepared by molding expandable particles or beads of a thermoplasticresin such as polystyrene in a closed cavity, often called bead board,are especially popular. Methods and apparatus for the preparation ofsuch boards have been widely described in the prior art, for instance,in US. Pat. Nos. 2,787,809, 3,408,690, 3,594,461 and others. Suchmethods produce boards having a general block orslab-like-configuration.

Further shaping and sizing of the molded blocks requires a cuttingoperation to be performed. For instance, in ordinary buildingconstruction where the board may be used as the insulation for walls andceilings, a tongue-and grooved board which is applied to the studding orunder-surface is commonly used. Insulation boards have also beenproduced which have grooves or vents cut into certain of their surfacesin order to permit passage of moisture vapor. Such a board is describedin US. Pat. No. 3,619,961. Grooved or channeled insulation boards havealso been produced which are in the form of laminates of cellularthermoplastic polymer core material with surface coverings of, forexample,paper, fabrics and cellular or non-cellular synthetic resin.Such laminates are described for example, in US. Pat. Nos. 3,619,961 and3,677,874.

In order to cut or channel the board, some of the material of theoriginal board must be removed. Board formed of expanded polymeric beadshas a definite degree of cohesiveness and stability, but due to itsparticular construction, it does not cut or rout well. The waste beadmaterial breaks up, flies around and sometimes the saws used tear chunksout of the bead board rather than making a neat cut. The cutting orrouting operation thus produces many flying particles of the polymericmaterial which accumulate about the cutting area presenting a bothersomeand hazardous situation.

SUMMARY OF THE INVENTION the jagged or discontinuous edge of aconventional saw' blade. The board is, in effect sliced rather thansawed by the smooth-edged rotating knives. Portions of the board can beremoved by using a pair of such knives positioned to make intersectingcuts. in the board.

combination with the heated tool. The board is initially sliced by theknife or knives and the area defined by the knife slit or slits isrouted out by the heated tool.

In a particularly preferred embodiment of the invention, laminatedcellular thermoplastic insulation boards are cut and grooved in themanner described above and surface laminations, such as those describedin US. Pat. Nos. 3,619,961 and 3,677,874, are applied in the form of acontinuous sheet material. The laminates may be adhered using apreviously applied adhesive material or the laminations may be adheredby heat-softening the surface of the core material and/or the surface ofthe lamina to be applied, and thereafter pressing the two together. Theapplication of the surface lamina in the form of a continuous sheet tothe upper and lower surfaces of the board makes it possible to employsepa rate or discontinuous lengths of board as the starting or feedstock material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of an apparatusperforming the aforedescribed process;

FIG. 2 is a detail, in perspective view, of the channelforming operationshown in FIG. 1;

FIG. 3 is a detail, in perspective view, of the heated tool performingthe channeling operation;

FIG. 4 is a detail, in perspective view, of the formation of a tongue inan insulation board according to an embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, insulation board 11 of expanded polystyrene beads previouslymolded into a generally rectangular slab by an conventional manner, isintroduced to the nip of a pair of drive rolls 12 and 13. Lower rolls,13, 20, 26 and 32 are suitably supported by frame 10. Upper rolls 12,19, 15 and 31 may be supported by an extension of such frame (not shown)as may be upper heater 17, upper laminate supply roll 23 and upper knife27. Drive rolls l2 and 13 direct the board to a lamination area where acontinuous sheet 21 of laminating material is unwound from supply roll23 and is pressed into contact with the upper surface of board 11 at nip15 by the laminating roll 19. An upper heating unit 17 of conventionaldesign directs heat into the nip 15 causing the surface of the board tosoften and become adherent. In similar fashion, a continuous sheet 22 oflaminating material is unwound from lower supply roll 24 and is adheredto the lower surface of the board at the nip 16 due to the combinedaction of heater l8 and laminating roll 20. The laminating materials 21and 22 may be of the same or different flexible sheet material, forinstance, Kraft paper, metallic foil, a fabric web or a cellular ornon-cellular polymeric film. The thus laminated board is drawn from thelaminating area by a pair of drag rolls 2S and 26 to a shaping areawherethe desired shaping is performed.

FIG. 1 shows the formation of a groove or dado in the side of the boardaccording to a preferred method of the invention. Spaced rotatingcircular knives 27 and 28 form two parallel slits in the side of theboard. The knives have a smooth, continuous edge and thus slice ratherthan saw the board. Thereafter, a heated tool 29, the configuration ofwhich is best shown in FIG. 3, removes the stock material from betweenthe two slits in the form of a continuous strip 38. Tool 29 has arectangular, flat bottom surface. the lead or cutting edge 39 beingtapered as shown in FIG. 3, that is, is sharpened on the inside of thetool. The width of the tool corresponds to the width of the groove to bemade in the side of the board. The tool is heated by means of aconventional element or cartridge located in the rearward end of thetool. The temperature of the tool is regulated by control means 30 shownin FIG. 1. The tool has upstanding lateral side walls 33 and 40configured as shown in FIG. 3.

As is best shown in FIG. 2, the heated tool edge 39 contacts the boardand the material is simultaneously softened or melted and sliced by thetool. The continuous strip 38 produced is pushed outward from the boarddue to the angle of the edge 39 and the upstanding side walls 33 and 40of the tool. The combined use of the spaced knives to make thelongitudinal slices and the heated tool to scoop or remove the stockpermits close control of the dimensions of the groove. The side walls ofthe groove are smooth and straight. The bottom wall of the groove isalso smooth and has a somewhat glazed surface due to the heating actionof the tool edge.

FIG. 4 illustrates one manner of forming a tongue in the side edge ofthe board. Little or no polymeric particles or dust are produced usingthis method wherein two pairs of the rotating, smooth-edged knives areemployed to cut the board. Blades 34 and 36 produce intersectinglongitudinal slices in the side and upper surfaces, respectively, of theboard to form the 4 upper rabbet portion of the tongue. Blades 35 and 37produce intersecting slices in the side and lower surfaces,respectively, of the board and form the lower rabbet portion of thetongue.

The temperatures employed at the laminating areas and the temperature ofthe lead edge of the tool, will of course depend upon the particularpolymeric resin making up the board. Polystyrene softens in thetemperature range of from about to 230F. and thus the temperaturemaintained at the nips l5 and 16 shown in FIG. 1 and the temperature ofthe lead edge of tool 29 should be at least within this range whenfoamed polystyrene insulation board is employed.

It is claimed:

l. The method of forming a groove in a surface of a foamed thermoplasticresin insulation board, said method comprising the steps of firstforming a pair of spaced continuous slits in said surface, said slitshaving a depth corresponding to the depth of the groove to be made insaid board; applying a knife-edged tool to the area defined by saidslits, said tool having a flat, elongated rectangular bottom having achisel-shaped leading knife edge tapered on one 'side to direct boardstock away from said surface and a width corresponding to the width ofthe area defined by said slits, said tool further having upstanding sidewalls rearward of said leading edge and perpendicular to said bottom;and causing said heated tool to move in said defined area'relative tosaid board while heating said tool to simultaneously soften and separatethe portion of foamed material defined by said slits from said board andto direct said separated portion outwardly from said board in the formof a continuous strip.

2. The method of claim 1 wherein said board is formed of expandedpolystyrene beads.

3. The method of claim 1 wherein said tool is heated to a temperature ofat least 190F. I I

1. The method of forming a groove in a surface of a foamed thermoplasticresin insulation board, said method comprising the steps of firstforming a pair of spaced continuous slits in said surface, said slitshaving a depth corresponding to the depth of the groove to be made insaid board; applying a knife-edged tool to the area defined by saidslits, said tool having a flat, elongated rectangular bottom having achisel-shaped leading knife edge tapered on one side to direct boardstock away from said surface and a width corresponding to the width ofthe area defined by said slits, said tool further haVing upstanding sidewalls rearward of said leading edge and perpendicular to said bottom;and causing said heated tool to move in said defined area relative tosaid board while heating said tool to simultaneously soften and separatethe portion of foamed material defined by said slits from said board andto direct said separated portion outwardly from said board in the formof a continuous strip.
 2. The method of claim 1 wherein said board isformed of expanded polystyrene beads.
 3. The method of claim 1 whereinsaid tool is heated to a temperature of at least 190*F.